• 플랜트 저널
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• 제6권2호
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• pp.62-69
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• 2010

The stability of coal pulverizer in the 800 MW coal-fired plants is vital to maintain their performance. Thus, this study analyzed the uneven abrasion of the deflector and coal spillage due to the air velocity maldistribution in the vane wheel of a bowl-type pulverizer as it is a possible cause for problems of facility using pulverized coal. In addition, air flow in the underbowl of a bowl-type pulverizer was studied to check air velocity maldistribution in the vane wheel using numerical method. In an attempt to correct the maldistribution of air velocity, air flow of the modified duct vane was studied as enlarging the length of the duct vanes installed at the air inlet duct of the pulverizer and increasing the angle of inclination. It was found that modified duct vane make the velocity distribution at the vane wheel uniform. formed by the duct vanes installed at the air inlet duct of the pulverizer and swirling flow is the major factor in making the velocity distribution of vane wheel exit uniform. This can prevent the uneven abrasion of the deflector, which is one of the components inside the pulverizer and coal spillage.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 추계학술대회논문집B
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• pp.688-692
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• 2001

Three-dimensional experimental analyses were conducted in the pulverizer simplified isothermal model. The experimental model was constructed on a 1/3.5 scale of 500MW pulverized coal boiler. The purpose of this study is to investigate the characteristics of coal particle separator and the pressure loss in the pulverizer models with dynamic classifier. Without regards a shape of separator top, the results showed that the increase of dynamic classifier rpm was induced in finer coal particle. But the capacity of total mass per minute was reduced. Also, the increase of dynamic classifier rpm had no effect on total pressure loss, but an increase of inlet velocity was induced that the rise of total pressure loss in the pulverizer models with dynamic classifier.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2001년도 춘계학술대회논문집D
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• pp.721-725
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• 2001

The main reason for applying pulverizer classifier-rotary type in fossil power plant is boiler high efficiency and energy saving movement in the government. This study intends to analyze the boiler efficiency through the pulverizer classifier-rotary type improvement in thermal power plant and makes its comparison to that of the used fixed type.

• 한국안전학회지
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• 제30권3호
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• pp.26-31
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• 2015

This paper describes the characteristics of voltage drop and thermal for poor connection on electrical connector of circuit breaker in control box of small size pulverizer. In order monitor, we did the changes of RMS in voltage and temperature value with video and made normal state over $2.5N{\cdot}m$ and poor connections state below $0.2N{\cdot}m$ by screw gage. In case of voltage signal, the voltage drop was increased when the current was increased due to poor connections. In case of temperature signal, the temperature difference indicates ten times at 5A and fourteen times at 15A in the normal state. According to increase thermal energy, the insulation of electrical wiring and connector of circuit breaker can be carbonized. The results of this study will be useful to the development of preventive devices and system for electric fire by poor connection at small size pulverizer.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2003년도 추계학술대회
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• pp.385-389
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• 2003

Three-dimensional experimental analysis was conducted in the pulverizer simplified isothermal model. The experiment model was constructed on a 1/3.5 scale of 500MW pulverizer. The purpose of this study is to investigate the effect of design parameters on the pulverized coal separator efficiency. Where used pulverized coal separator design parameters are guide vane angle, static classifier angle, dynamic classifier rpm. Taguchi method was used to find the effective design parameters related to pulverized coal separator efficiency. The results of the experiment showed that guide vane angle and dynamic classifier rpm were the design key parameters. In addition to the total number of experiment cases were reduced by Taguchi method.

• 동력기계공학회지
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• 제18권6호
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• pp.34-39
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• 2014

In this study, the structural analysis and the modal analysis are conducted to investigate the stress level, the deformation characteristics and the natural modes of the casing of a planetary gear reducer for a 800kW grade pulverizer mill. The casing is subjected to the load, 2800 kN, from the lump coals in the pulverizing process. Because of the symmetry, the half portion of the reducer casing is modeled for the stress analysis. But the full model is used to find out the eigenvalues and natural modes for the modal analysis. The contact conditions are applied between the thrust pad bearing and the adjacent contacting parts. The results shows that the casing structure has the sufficient strength and stiffness to support the load under consideration. ANSYS version 15 is employed to perform the numerical study.

• Journal of Nutrition and Health
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• 제42권8호
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• pp.740-749
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• 2009

본 연구는 ultra-fine pulverizer 또는 nano-scale pulverizer로 초미세분쇄시켜 입자크기가 감소된 옥수수전분의 섭취로 인한 생리적 기능성을 탐색한 결과는 다음과 같다. 1) 각 실험식이군의 식이 섭취량은 UFC군, NAC군은 차이가 없었으며, NSC군에서 유의하게 낮았다. NSC군의 식이 섭취량이 낮았음에도 불구하고 체중증가량이 많아 식이효율은 NSC군에서 가장 높았다. 2) 간, 신장의 무게는 UFC군 > NSC군 > NAC군순으로 높았다. 3) 소장의 무게는 UFC군이 NAC군에 비해 유의하게 높았으며, 소장의 길이는 각 실험군에서 유의적인 차이가 없었으며 맹장의 무게 및 장통과 시간도 유의적인 차이가 없었다. 4) 맹장내 단쇄지방산의 함량은 NSC군이 UFC군이나 NAC군에 비해 유의하게 높아 장내 미생물에 의한 발효가 활성화되고 있었으며 장내 Bifidobacterium 증식도 NSC군이 다른 군에 비해 활발하였다. 5) 소장세포의 증식은 NSC군에서 낮았다. 이상의 결과로 볼때 nano-scale로 입자의 크기가 감소된 옥수수 전분은 소화흡수율을 증가시켜 성장능력을 증진하는 것으로 나타났으며, Bifidobacterium 증식 촉진, 단쇄 지방산 생성을 촉진하는 효과를 갖고 있어 상대적인 영양밀도를 높이는 기능성을 갖고 있는 것으로 나타났다. 따라서 장기능이 미숙한 유아기, 장기능이 불완전하거나 미약한 환자, 노인등의 특수목적 영양식의 기본재료로 활용될 수 있음을 제안한다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1668-1671
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• 2005

Vulcanized natural rubber was pulverized using a single screw extruder in a non-cryogenic Solid Shear Extrusion process where rubber granulates were subjected to high compressive and shear stresses. The producted particles had diameters ranging from 40 to 1200$\{mu}m$. A principle used in this paper was developed in Russia. The development method for producing a polymeric material powder consists in compressing said material by shearing the material during a pressure increase and cooling. Consecutive breakdown is carried out by shearing the material during the pressure decrease and cooling.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1694_1695
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• 2009

In this paper, the coal mass flow of the pulverizer used in the coal-fired power plants is modeled in view of the controller design rather than the educational simulator. The coal mass flow is modeled by reinvestigating the mass balance models physically. To identify the model parameters, the Matlab Simulation Tool is used with the data gained from a plant database. It can be seen that the simulated model outputs are well matched with the measured ones.

• Smart Structures and Systems
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• 제22권2호
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• pp.185-192
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• 2018

Participants in the Asia Pacific Conference of the Prognostics and Health Management Society 2017 (PHMAP 2017) Data Challenge were given measured vibration signals from motor-driven gearboxes used in pulverizers. Using this information, participants were requested to predict failure dates and the faulty components. The measured signals were affected by significant noise and disturbance, as the pulverizers in the provided data worked under actual operating conditions. This paper thus presents a fault prediction method for a motor-driven gearbox in a pulverizer system that can perform under external noise and disturbance conditions. First, two fault features, an RMS value in the higher frequency zones (HRMS) and an amplitude of a period for high-speed shaft in the quefrency domain ($QA_{HSS}$), were extracted based on frequency analysis using the higher and lower sampling rate data. The two features were then applied to each pulverizer based on results of frequency responses to impact loadings. Then, a regression analysis was used to predict the failure date using the two extracted features. A weighted regression analysis was used to compensate for the imbalance of the features in the given period. In addition, the faulty components in the motor-driven gearboxes were predicted based on the modulated frequency components. The score predicted by the proposed approach was ranked first in the PHMAP 2017 Data Challenge.